Nitrophenylthiogylcollic acids



Patented Mar. 19, 1935 UNITED STATES Blackley, Manchester,

Imperial Chemical Industries .poratlon of Great Britain No Drawing. Application August 11, 1933, Serial No. 684,750. In Great Britain August 17, 1932 2 Claims.

7 This invention relates to a new process for the manufacture of a dinitrophenylthioglycollic acid and for the manufacture of a new intermediate by reduction thereof. 4 According to the invention we treat 2:4-dinitrophenylmercaptan with, halogeno'acetic acid, e. g.-, chloroacetic acid, in the presence of an alkaline carbonate or other mildly alkaline fixative for mineral acid to give the known 2 4-dinitrophenylthioglycollic acid. We then reduce this compound to obtain a new and valuable dyestuif intermediate, namely, 2-nitro-4-aminophenylthioglycollic acid. A convenient means of effecting this reduction is by means of an alkaline sulfide, but we do not confine ourselves to this. reducin agent, Other reducing agents, as for example nascent hydrogen may be used. The following examples illustrate, but do not limit, the invention. The parts are by weight.

Example I Two hundred two and five-tenths parts of 1- chloro-2z4-dinitrobenzene are converted to 2:4- dinitrophenylmercaptan by the method of Willgerodt, Berichte der deutschen chemischen Gesellschaft, 17, Ref. 322. The mercaptan paste obtained is condensed with sodium chloroacetate as follows: The mercaptan is suspended in 1500 parts of water with 108 parts of sodium carbonate and stirred at ordinary temperature. 'One hundred twenty parts of monochloroacetic acid are neutralized cold in 800 parts of water with sodium carbonate. The solution is added to the mercaptan liquor at C. and the whole warmed to 80 C. in one hour. After stirring one hour at this temperature, the solution is filtered from suspended matter and the thioglycollic acid precipitated at 40 C. with hydrochloric acid. The 2:4- dinitrophenylthioglycollic acid is filtered off and reserved as paste. The dried product has melting point of 172 C.

The reduction of 2: i-dinitrophenylthioglycollic acid to 2-nitrol-aminophenylthioglycollic acid is carried out as follows: Two hundred parts of 2:4-dinitrophenylthioglycollic acid are suspended in 2000 parts of water at 80 C. and dissolved by addition of ammonia. A solution of 280 parts of sodium sulfide crystals in 1000 parts of water is gradually added at 80 C. dur- 0 ing one-half hour. During the addition, the solutions becomes orange in color. After one-half hour at 80 C. to 85 C. the solution is cooled to C. and treated with 300 parts of concentrated hydrochloric acid. The acidified liquor is stirred with 20 parts of charcoal, filtered from suspended at 80 C. for half an hour,

PATENT) OFFICE England, assignors to Limited, a cormatter and the nitroaminophenylthioglycollic acid precipitated from solution by neutralization to Congo red paper with ammonia. The product is filtered, washed with cold water, and dried at C.

The product is an orange-yellow substance which dissolves readily in dilute aqueous acids and alkalies; When crystallized from hot water, orange leaves are obtained having melting point of 168 C.

Example 11 I Two hundred parts of 2:4-dinitrophenylthio glycollic acid are dissolved in 2000 parts of water at C. by adding enough-ammonia. Then 400 15 parts of 30% sodiumhydrosulfide solution are I added with stirring during five minutes. The solution is kept at 80 C. to C. for half an hour. Reduction is then complete. The deep orange solution is acidified with hydrochloric acid 20 and the nitroaminophenylthioglycollic acid isolated as described in Example I.

Example III To 200 parts of 2:4-dinitrophenylthioglycollic 25 acid, dissolved in aqueous ammonia as described above, are added parts of ammonium chloride and a solution of 280 parts of sodium sulfide crystals in 1000 parts of water. Themixture is stirred hydrochloric acid, and the nitroaminophenylthioglycolllc acid is isolated as in Example I.

Example IV To 200 parts of 2:4-dinitrophenylthioglycollic acid, dissolved in aqueous ammonia at 80 C.. as described above, is gradually added a solution of sodium trisulfide prepared by mixing 18.5 parts of sodium sulfide crystals and 5 parts of sulfur, and warming until the sulfur has dissolved. The 40 solution is kept at 80C. for a further half hour, cooled to 40 C. and the nltroaminophenylthiogly-' collie acid isolated as described in Example I.

Example V To a solution of 200 parts of 2:4-dinitrophenylthioglycollic acid in 2000 parts of dilute aque- I ous ammonia at 80 C. 280'part's of magnesium sulfate crystals are added. -/"A solution of 280 parts of sodium sulfide cry tals in 1000 parts of water is now gradually added during half an hour, keeping the temperature at 80 C. After a further half hour, the solution is'heated and the product isolated as described in Example I.

Other reducing agents which may be employed cooled, acidified with 30.

according to this invention are potassium sulfide, We claim:

potassium hydrosulfide and potassium polysul- 1. In a processor producing a thioglycollic fides. In general, alkaline sulfidesare preferred. acid, the step which comprises reducing 2:4-dini- By alkaline sulfides" is meant sulfides which trophenylthioglycollic acid with an alkaline sulhave an alkaline reaction in water solution. fide. v

The products are especially valuable for use 2. A compound being most probably 2-nitroas intermediates in the production of dyes. 4-aminophenylthioglycollic acid, said compound As many apparently widely difierent embodibeing an orange-yellow substance which dissolves ments of this invention may be made without readily in dilute aqueous acids and alkalies, and departing from the spirit and scope thereof, it crystallizes from hot water in orange leaves hav- 10 is to be understood that we do not limit ouring a melting point of about 168 C. selves to the specific embodiments thereof except NORMAN HULTON HADDOCK. as defined in the appended claims. FRANK LODGE. 

